Tool life monitoring during the diamond turning of electroless Ni-P

Diamond tools become severely worn when machining Ni-P plating materials. Tool life monitoring is therefore essential to avoid the deterioration of workpiece quality. In this paper, in order to better detect tool life while the tools are in use, detailed investigations of the cutting force and acoustic emission (AE) measured during diamond turning process have been made. The results of this tool-life testing show that the cutting force and AE supply valuable information on tool failure; the dynamic component of the thrust force fluctuates chaotically when the tool dulls. This phenomenon can be detected using the 1/f(beta) power spectrum with a spectral exponent of beta > 1. On the other hand, the AE amplitude a tends to rise just when chipping occurs on the cutting edge. This feature can be detected by the amplitude distribution spectrum, in which the AE event rate follows the power law a(-m) with a scaling exponent of m < 2. Therefore, we can conclude that a spectral exponent of beta > 1 and a scaling exponent of m < 2 can be used as the criteria to gauge tool life, because it was observed at the end of the tool life -that tool comer had become wom out and that chipping had occurred on the cutting edge. (c) 2006 Elsevier Inc. All rights reserved.